The use of elements for ventilating known housings in the automobile industry or of vehicles in general is known to be widespread; these ventilation elements for example are associated with apertures in containers of electrical or electronic parts (such as the optical units or headlamps of motor vehicles) or of mechanical parts (gearboxes, hydraulic transmission members, window opening systems or windscreen wiper units, for example) where the pressure must be equalized between the interior of these containers and the external environment. An element of the aforesaid type is usable in every component, not necessarily in the automobile industry, where said need for pressure compensation/equalization exists (for example electrical control panels, street lighting systems, chemical product containers or cans).
These ventilation elements are also known to have a form such as to limit water entry into said containers or housings, such water deriving from rain or puddles or from vehicle or engine washing. For example a ventilation element is known from EP1102002 comprising a cylindrical cover member closed at one end and open at the opposite end in which a substantially cylindrical body is inserted. An air passage is formed between the inner wall of said member and the outer wall of the internal body and between the lower surface of the member and the lower end of said body. A plurality of projections are positioned at predetermined intervals along the periphery of the internal body; when said body is not coupled to the cover member, its outer diameter (including the projections) is greater than that of the member, whereas when the body is inserted into the member, its projections enter into contact with the inner wall of said member so that the body becomes positioned and fixed in this latter to create the air passage between the projections.
A hydrophobic membrane can be associated with the internal body at that end of this latter internal to said cover member.
In the aforesaid known solution, the ventilation function of the subject element of the patent and the connection function between the cover member and the internal body are both achieved by the internal body projections which maintain it spaced from the wall of the cover member. This involves the need for careful specific design of the internal body to ensure suitable ventilation of the housing.
Moreover, as the internal body is yieldable, it can deform on insertion or with the passage of time (“relaxing”) to hence modify the cross-sections of the air passages, and thus modify the ventilation of the housing with which the ventilation element is associated.
In addition, the internal body can enter into contact with foreign elements which penetrate from the open end of the protection member, hence undergoing damage.
Furthermore, in the known solution, the internal body, of yieldable material, projects from the cover member and is connected to the housing. This requires careful design of the ventilation element to obtain correct shaping of said body and member such as to achieve a correct and reliable sealed connection to the relative housing. In addition, after coupling the body of yieldable material to the housing it is difficult to separate it from this latter when the ventilation element needs to be removed.
Moreover, the aforesaid known solution (and other known equivalents in the technical field) presents a large rubber portion (internal body), involving a considerable cost for the finished product, and lengthy production times related to the moulding of the internal body.